THE NATIONAL GEOGRAPHIC MAGAZINE
Photograph by J. C. Clarke
EXTRACTING A CORE FROM A LOG AT WUPATKI
When impracticable to cut a cross-section from a log, the necessary data which its tree rings
record can be obtained by drilling the beam and removing the core (see page 760).
pottery of the linking era, came between
the red and the yellow. This was an im
portant guide in the selection of ruins for
our subsequent search.
A BIT OF CHARCOAL GIVES A VALUABLE
DATE
When I first became interested in the
possibility of dating prehistoric ruins
through tree rings I was very particular
as to the specimens worth looking at. I
told the archeologists that only pine beams
six inches or more in diameter and in
good condition could be used, and it is
true a large number of first-class speci
mens enriched our collections. Then, to
extend the known chronology, specimens
were accepted in poor condition.
But many of the sections from Pueblo
Bonito were burned; we had to find a way
successfully to treat charcoal. At first frail
specimens were dipped in melted paraffin.
Later, this method was improved upon:
the fragments were soaked in a solution
of paraffin and gasoline. This solution we
now keep on hand, and fragile pieces are
immersed in it as soon as they come out
of the ground, or, if not, they are kept
covered by fresh earth until they can be
put in the solution. If the pieces are apt
to fall apart they are tied with string and
then soaked.
The first specimens from the Jadito
Valley ruins were mere chips scratched
from old debris heaps near the mesa edge.
These were brought to me with misgiv
ings, for many were only as large as one's
thumb, and a little pressure would crush
them to powder. But, to my surprise, we
found in some bits a series of rings closely
resembling those between A. D. 1365 and
1420. These pieces came from Kawaiku.
I attached a high degree of importance
to this dating, and yet refused to rely
upon it completely because too much de
pended on it; for, if correct, it would be
the first pre-Spanish ruin in the south
western United States to receive an actual
and exact date.
Absolute certainty was finally obtained
in a piece of charcoal as big as one's fist,
found in an old kiva at Kawaiku. The
rings looked favorable; we carefully bound
the fragment and soaked it in the paraffin